Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Qual é a classificação semanal máxima do ITV1?
 ###Tabelas: CREATE TABLE knights'_weapons_items_and_vehicles (knights'_weapons_items_and_vehicles_id AUTO_INCREMENT PRIMARY KEY, Knight VARCHAR, Weapon/item VARCHAR, External weapon VARCHAR, Shield animal VARCHAR, Cart VARCHAR) CREATE TABLE supplemental_first_round_selections (supplemental_first_round_selections_id AUTO_INCREMENT PRIMARY KEY, Pick INT, Player VARCHAR, Team VARCHAR, Position VARCHAR, School VARCHAR) CREATE TABLE past_champions_in_the_field (past_champions_in_the_field_id AUTO_INCREMENT PRIMARY KEY, Player VARCHAR, Country VARCHAR, Year(s) won VARCHAR, Total INT, To par INT, Finish VARCHAR) CREATE TABLE all-time_series_records_against_big_12_members (all-time_series_records_against_big_12_members_id AUTO_INCREMENT PRIMARY KEY, Texas vs. VARCHAR, Overall Record VARCHAR, at Austin VARCHAR, at Opponent's Venue VARCHAR, at Neutral Site VARCHAR, Last 5 Meetings VARCHAR, Last 10 Meetings VARCHAR, Current Streak VARCHAR) CREATE TABLE series_1 (series_1_id AUTO_INCREMENT PRIMARY KEY, # INT, Airdate VARCHAR, No. of couples INT, First couple VARCHAR, Second couple VARCHAR, Third couple VARCHAR, Fourth couple VARCHAR, Viewers (millions) VARCHAR, ITV1 weekly ranking INT)  
SELECT MAX ITV1 weekly ranking FROM series_1